package com.us.usws.support.filter;

import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Encoding filter
 * @author Wang Jianbo
 */
public class SetEncodingFilter implements Filter {
	private static Log log = LogFactory.getLog(SetEncodingFilter.class);

	private String ignoreExp = "";

	/**
	 * The default character encoding to set for requests that pass through this
	 * filter.
	 */
	protected String encoding = null;

	/**
	 * The filter configuration object we are associated with. If this value is
	 * null, this filter instance is not currently configured.
	 */
	protected FilterConfig filterConfig = null;

	/**
	 * Should a character encoding specified by the client be ignored?
	 */
	protected boolean ignore = true;

	/**
	 * Take this filter out of service.
	 */
	public void destroy() {
		this.encoding = null;
		this.filterConfig = null;
	}

	/**
	 * Select and set (if specified) the character encoding to be used to
	 * interpret request parameters for this request.
	 *
	 * @param request  The servlet request we are processing
	 * @param response The servlet response we are creating
	 * @param chain	The filter chain we are processing
	 * @throws IOException	  if an input/output error occurs
	 * @throws ServletException if a servlet error occurs
	 */
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
		HttpServletRequest req = (HttpServletRequest) request;
		String path = req.getServletPath();

		if (ignore || ignoreExp == null || checkMatch(path, ignoreExp)) {
			chain.doFilter(request, response);
			return;
		}

		if (request.getCharacterEncoding() == null) {
			request.setCharacterEncoding(selectEncoding());
			response.setCharacterEncoding(selectEncoding());
			log.trace("Set " + req.getServletPath() + " to " + selectEncoding());
		} else {
			log.trace("Current request has not encoding,please check!");
		}
		chain.doFilter(request, response);
	}

	/**
	 * Check whether str matches the regex
	 *
	 * @param str   servlet path to be checked
	 * @param regex regex to be ignored
	 * @return true if matches, false if not.
	 */
	private boolean checkMatch(String str, String regex) {
		Pattern p = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);
		Matcher m = p.matcher(str);
		return m.find();
	}

	/**
	 * Place this filter into service.
	 *
	 * @param filterConfig The filter configuration object
	 */
	public void init(FilterConfig filterConfig) throws ServletException {

		this.filterConfig = filterConfig;
		this.encoding = filterConfig.getInitParameter("encoding");
		String value = filterConfig.getInitParameter("ignore");
		this.ignoreExp = filterConfig.getInitParameter("ignoreExp");

		if (value == null)
			this.ignore = false;
		else if (value.equalsIgnoreCase("true") || value.equalsIgnoreCase("yes"))
			this.ignore = true;
		else
			this.ignore = false;
	}

	/**
	 * Select an appropriate character encoding to be used, based on the
	 * characteristics of the current request and/or filter initialization
	 * parameters. If no character encoding should be set, return
	 * <code>null</code>.
	 * <p/>
	 * The default implementation unconditionally returns the value configured
	 * by the <strong>encoding</strong> initialization parameter for this
	 * filter.
	 */
	protected String selectEncoding() {
		return (this.encoding);
	}

	/**
	 * Returns the filterConfig.
	 *
	 * @return FilterConfig
	 */
	public FilterConfig getFilterConfig() {
		return filterConfig;
	}

	/**
	 * Sets the filterConfig.
	 *
	 * @param filterConfig The filterConfig to set
	 */
	public void setFilterConfig(FilterConfig filterConfig) {
		this.filterConfig = filterConfig;
	}

}
